What's Behind the Great Dip in US Carbon Emissions?

CO2 Emissions at Lowest Levels in 20 Years

In the winter of 2012, carbon emissions belched forth by the power-generating sector in the world's largest economy hit their lowest levels in 20 years. Mat highlighted the EIA study that bore the good news earlier this month, and it looks like the trend is likely to continue.

Energy production in the U.S. produced around 1,340 million metric tons of carbon dioxide emissions during the first three months of this year, just two million metric tons more than the same three-month period in 1992. Along the way, first-quarter emissions reached a high of nearly 1,580 million metric tons, in 2004. Last year’s first-quarter total was 1,453.

In this chart, fluctuations within a single year reflect the sharp rises in demand during especially cold or hot months. The black line represents the 12-month moving average. Emissions dropped sharply in 2009 due to the global recession, rebounded in 2010, and now appear to be in gradual decline.

As we've pointed out before, this decline in CO2 emissions is attributable primarily to the rise of natural gas—the stuff is now cheaper than coal, and power plants are switching over. For the first time in half a century, the amount of electricity we generate from coal has dipped below 40%.

But a number of other factors deserve notice as well. The recession was one. But chief among them, the EPA's incoming greenhouse gas regulations (and other pollution rules aimed at coal plants) are surely working to convince power companies to make the switch, and they'll help ensure that coal stays boxed out should the price of nat gas spike again. Meanwhile, renewable energy's share of the mix continues to grow, and automakers are steadily ramping up vehicle efficiency to meet tightening CAFE standards.

We're still not reducing emissions nearly fast enough to meet the targets laid out by climate scientists, but we're finally headed in the right direction. If we keep it up, maps like this may soon tell another story: